The drawing process, as the name suggests, involves using a head press to reduce the size of the steel bar head, and then using tensile force to pull out the larger diameter low-carbon steel material (i.e., the steel bar) from the conical hole. During this process, the diameter of the steel gradually decreases. After multiple draws, fine-diameter steel wires can eventually be produced. In short, when steel is drawn above the recrystallization temperature after heating, the resulting steel wire is called hot-drawn wire. The drawing process carried out at room temperature is called cold drawing wire.
Hot-drawn wire exhibits excellent plasticity, is easy to form, and there is no internal stress in the steel after forming, which is convenient for subsequent processing procedures. In contrast, cold-drawn wire has the characteristic of cold work hardening. Cold rolling and cold drawing both fall within the category of cold working, and this type of processing can cause work hardening. Work hardening refers to the phenomenon where, as plastic deformation increases, the strength and hardness of a metal rapidly rise, while its plasticity and toughness rapidly decline.
The main basis for distinguishing cold working from hot working is the recrystallization temperature. Pressure working carried out below the recrystallization temperature is classified as cold working, during which work hardening occurs. Processing carried out when the temperature is higher than the recrystallization temperature is considered hot working, and the work hardening phenomenon that occurs at this time will be eliminated by recrystallization.
Although both cold rolling and cold drawing can cause plastic deformation and diameter reduction of wire rods, there are significant differences in their properties. Cold rolling is a phenomenon of diameter reduction that occurs during the processing, while cold drawing achieves the target size by intentionally reducing the diameter. Therefore, their performance varies greatly.